Posted
by
timothy
on Sunday April 22, 2012 @01:21AM
from the first-the-moon-now-this dept.

gambit3 writes with this news, carried by the BBC: "Scientists say the notoriously dry continent of Africa is sitting on a vast reservoir of groundwater. They argue that the total volume of water in aquifers underground is 100 times the amount found on the surface. Across Africa more than 300 million people are said not to have access to safe drinking water. Freshwater rivers and lakes are subject to seasonal floods and droughts that can limit their availability for people and for agriculture. At present only 5% of arable land is irrigated."

More resources means people will think they can make more people. Which, of course, will be worse in the long run since underground water never lasts forever, and it will be a larger population to starve.

Indeed. As long as the people there do not understand what their problems are, they will not get out of their current situation. Education is the only way to achieve that. "Gifts" from the west only result in laziness, which is one primary enemy of education. Most people are only willing to learn if there is no alternative. Sad but true.

Also known economic circumstances as dumping [wikipedia.org]. The local costs of production can't compete with 'free', and so local production is stymied by what is effectively first world governments subsidising domestic production.

Africa needs infrastructure built and maintained by locals. You can still find the ruins of plenty of bridges, roads, etc. built by the British, the French, etc. People only value infrastructure if they had to bleed themselves to build it.

Africa needs infrastructure built and maintained by locals. You can still find the ruins of plenty of bridges, roads, etc. built by the British, the French, etc. People only value infrastructure if they had to bleed themselves to build it.

Not necessarily true. I value a lot of roads that were built before I was born. I think that what is important is the expectation that people's work and taxes will have to maintain it. I could extend that to say that if someone built a road out of charity to a remote region this could be good for the locals, and if the expectation was that the new trade paid for the upkeep it would increase the economy.

The issue with "free" infrastructure isn't moral hazard. It's expertise and cost. If nobody around knows how to maintain a road, it won't be maintained, regardless of short-term economic benefit. Similarly, if the road or bridge doesn't bring enough benefit to the local economy to pay for maintenance, it won't happen.

This is the real problem with dumping and helicopter development (i.e. flying foreign engineers and crews in to build something, then going home) - the economic incentives from this behavior

Bullshit. The reason the roads built by European countries grew dilapidated was because they were useless for the locals' travel and commerce. When European powers colonized Africa, they just build roads leading straight from villages to port towns, paying more for goods than the locals could and consequently pretty much killing all trade between villages. The roads they built were generally in tropical areas where the cement couldn't dry before getting doused in rain, and the undergrowth constantly damaged what the rain hadn't. So even if the roads that Europeans built were useful in any way for the Africans themselves, they still wouldn't have lasted until the present day.

I've heard of stories where Chinese road-building companies would use local labour with picks and shovels to build roads during the day (to keep the local Big Men happy), and then send in Chinese workers with heavy earthmoving equipment to do the actual work.

Not training the locals was a deliberate strategy by the Chinese to prevent skilling up the local workforce and giving them ideas that they might be able to complete.

As always with the Chinese -- it's ALL about self-interest. The Han will always come fi

At this point, you guys are just circle-jerking. One bashes Africa and gets a +5, then another replies and bashes Africa getting a +5 repeatedly. I personally think Africa's problem has been nations repeatedly coming in with devastating weapons and laying claim to its resources. And when the people try to take it back they are faced with guns. And the people who took their resources will justify this by identifying one African as the representative of them all who, has agreed to sign everything over even though nobody else accepts this person as their leader. Kind of like when a law gets passed in the United States that nobody wants.

Most of Africa's current problems are due to very bad government. When your country is run by an immoral, thieving, crazy, gangster, the general population is unlikely to succeed. It is time to stop blaming the very real ills of colonization on the today's issues. There are successful nations in Africa and they all have competent to very good governments,and rule of law.

It's like blaming your parents for you being neurotic at 20 might be credible. At 45, not so much: you've had plenty of time to straighten your own shit out, so stop blaming mom and dad.

I'll be the first to point out that colonial powers did heinous things in Africa.I'll also be one of the only ones pointing out that they likewise brought those countries into the modern era (not for altruistic reasons, except perhaps some missionaries) with th

I think you are confusing Africa with Asian countries like India and Bangladesh. They don't have the culture of huge families in most of Africa (except where there are large Asian populations).

They also understand the value of education. Most African children are actually desperate to go to school. Most is the non-energency charity is focused on building schools and giving children the opportunity to attend.

Most people in Africa have enough to eat. Africa is an enormous continent with many different landscapes and people. What Africa needs is leaders who actually care for their people, so they can exploit the land better and be educated.

Most people in Africa have enough to eat. Africa is an enormous continent with many different landscapes and people. What Africa needs is leaders who actually care for their people, so they can exploit the land better and be educated.

It's not that Africans can't pick the right leaders. It's that the people draining African resources will kill any African who tries to take the place of the leaders they've chosen for Africa.

Too many rednecks running around in pickup trucks with guns breeding then getting welfare handouts.

I drive a pickup and have several guns (4 atm, and will be getting several more in the next decade or so). I also have a Masters degree. Someone's choice in cars and their desire to exercise a Constitutional right does not have any bearing on their intelligence or economic situation.

Do you believe in creationism? And why have a gun anyway? - arguing that its a constitutional right is a fallacy.

No, I don't. And how is it a fallacy arguing that gun ownership is a constitutional right? It's expressly written. Or are you trying to say that it only applies to militias? You do realize that militias are citizens called up to fight in a local battle ARMED WITH THEIR OWN WEAPONS. And the fact that the writers of the Constitution made it the second amendment, and not the 10th, shows that they valued personal gun ownership just below the freedoms of speech, press, and assembly.

I looked at the map. Most of the blue areas were areas that are actually desert - the vast areas of Egypt (west of the Nile), Algeria, Niger, Chad, Namibia and so on. Aside from Egypt, most of these countries have very small populations, so population is not the problem there. In any case, nothing to worry - most of these countries are not interested in the well being of their populations, and so one is unlikely to see an overpopulation problem suddenly hit the Sahara and the Namib deserts.

People bread like rabbits once there is enough food and water to go around. They do anyway, but the infant mortality rate is high and migration to barren areas is very limited. Once there's food, water and safety, large groups of people migrate and breed. In just one or two generations, the country will be densely populated and there will once again be a shortage of resources.

I think the opposite is true. Infant mortality is high in these areas so they have more children in the hope some survive. When there is food, medicine, better sanitation etc, they breed less because there is less chance of the infants dying.

You see this bullshit all the time from people who never took more than BIO 100 and presume that humans work like bacteria. Turns out, they don't. The proof of that is first world nations. They all have at most low population growth, and many have neutral or negative population growth. The "human bacteria" theory says they should be the prime places for a massive booming population. There's abundance in everything and IMR is low so population should explode... But it doesn't.

Turns out when you solve the basic needs, when people have more than a subsistence living, when they don't have to worry about a bunch of their offspring dying, they stop having so many kids.

The way to control population is not to try and starve people of resources. You might notice that is the situation now and yet there's high birth rate. The way to control is to get people better lives. Sufficient food, clean water, medical care, shelter, etc and then the population growth is tamed.

This isn't a "Well we hope humans work like this," theory, it is how things HAVE worked. It is the reason there was no massive boom and crash in the US, Europe, Japan, and so on. Population growth has slowed, leveled off, or even inverted in all the places that have the most abundant resources.

The strategy of "Just let the brown people die," is not only extremely callous, it is also counter productive to getting a stable population level.

Seriously? You think we actually bother to ship water across oceans? Not hardly. All the bottled water you find gets bottled relatively locally. Nobody is going to pay ocean freight prices to ship water when you can get it from a municipal source at $5/750 gallons or so.

Actually, that is *exactly* what we do right now - with "Fiji" water being the biggest example - a spring with lots and lots of lovely water coming out of it that is bottled up and shipped to the US while the local population faces water shortages, all because people have been fooled into thinking that the Fiji water is somehow better than tap water.

You see this bullshit all the time from people who never took more than BIO 100 and presume that humans work like bacteria. Turns out, they don't. The proof of that is first world nations. They all have at most low population growth, and many have neutral or negative population growth. The "human bacteria" theory says they should be the prime places for a massive booming population. There's abundance in everything and IMR is low so population should explode... But it doesn't.

I'd be a bit more circumspect about my ability to judge the long term growth rates of humans just two generations after the introduction of the contraceptive pill and Roe vs Wade. It's like the equivalent of spraying some dilute poison in the petri dish that most but not every bacterium is affected by and thinking that the long term growth rates can be predicted by the growth rates of that bacteria in a few hours.

You have it the wrong way around. The argument isn't biological in nature, it deals with economics. People are not bacteria in a petri dish. They can think about the future and plan according to the means that are available to them. Children are the only investment available to many peoples in the poorest parts in the world, since they receive little care, but tend to take care of their parents. In the West, children bear a huge opportunity cost, as they need to be taken care of, but don't contribute directly to the well-being of their parents as much as the offspring in poorer nation.

This is why there is a lot more demand for contraceptives and abortions in the West, and that is why methods for birth control were developed in the first place.

There is a weird episode in the Bible where a guy called Onan was boning his brother's wife, and deliberately pulled out and soiled the carpet to avoid getting her pregnant. Got murders him for wasting his seed, despite being generally against adultery...

I know he said "go forth and multiply" but with your sister in law? And why are Catholics so against sex out of marriage when God seems to condone it as long as you try to get her pregnant?

There is a weird episode in the Bible where a guy called Onan was boning his brother's wife, and deliberately pulled out and soiled the carpet to avoid getting her pregnant. Got murders him for wasting his seed, despite being generally against adultery...

I know he said "go forth and multiply" but with your sister in law? And why are Catholics so against sex out of marriage when God seems to condone it as long as you try to get her pregnant?

Except God didn't murder him for wasting his seed, but for disobeying the law from Deuteronomy regarding providing an heir for a dead brother. The Catholic interpretation is so inane that it would be risible if it didn't do such harm.

A bigger question is why western religions are so interested in sex. Could it be because they are run by a group of horny old men? No, that surely couldn't have anything to do with it.

Western religions should announce they no longer give a two-headed rat's ass about sex, from now on they'll be more involved with the eternal verities of life, i.e., what does it all mean, why are we here, where shall we have lunch. If they would concentrate on those, there'd be much less strife caused by the religions. Well, getting rid of their voyeuristic pre-occupation with sex is one thing they can give up. They also need to give up their fear of women. I'd like to hear them proclaim to heavens they no long care what a woman wears as long as it is stylish and the colors don't clash.

As others have pointed out, this trend of those with higher incomes having fewer children is more than two generations old. It goes back to the Enlightenment period at least (our ability to track it further than that is limited). This trend has nothing to with abortion and/or modern contraception.

It isn't that less of their kids dying that leads to lower family counts, it is that they no longer need a large family to support them when they get old if there are enough government resources to help with the job. A large family is an expense, so in effect they are paying into an old age insurance system. Lower the expected expense for their later years and they'll forgo the current expense of a large family. Also, it helps if they can keep producing an income longer which is what education tends to do f

Also, one of the bigger factors in development and reducing birthrates is educating girls. There is a lot of research and practice behind it; it's widely accepted to work.

I don't know the exact reason, but I suspect that making half your population more productive would be a big help and empowering girls to control their lives also gives them power over their own reproductive systems.

Look at the population figures excluding immigration. For most of the EU, population growth is slightly negative if you discount immigration, which indicates that people are not breeding at below replacement rate.

With enough energy, we could distill sea water. Therefore pure fresh water is not a finite resource that must limit the earth's population anytime soon. This is a myth. There is also not (in principle) an energy shortage -- just technical obstacles to using more of the solar and geothermal energy that are available in such staggering abundance (compared to our current energy usage).

Out of curiosity, just what is the safe limit for boron/boric acid consumption in humans? I was under the impression that it was so high as to be inconsequential. It's pretty nasty stuff for insects, but not the rest of the animal kingdom AFAIK.

Except that evidence shows that improving the economic situation of people reduces the rate at which they reproduce. The problem with the chart you linked to is that I am pretty sure that in those countries, those with more education are also more wealthy. I am not exactly sure why you think that anybody would pay to import water from Africa. The logic of this article is that countries in Africa that suffer from severe droughts and starvation as a result could improve their food supply by using water from

More resources means people will think they can make more people. Which, of course, will be worse in the long run since underground water never lasts forever, and it will be a larger population to starve.

I personally think it's a bit inconsiderate to basically say there should be less Africans. The number of Africans in existance is not the root cause of their problem. My first thought was "what non-African nation is going to lay claim to this water supply while Africans continue to die?"

Actually, the opposite effect has been observed in real life. When people obtain (relative) wealth, and mortality (especially infant mortality) rates drop, the birth rate drops within a generation or two.

Florida was sitting on a vast, untapped groundwater reserve 100 years ago.

50 years ago it was starting to get tapped.

50 years from now, if usage trends don't change, Florida will need high powered desalination plants just to provide potable water to the populace, agriculture will be dead, and the whole place will bear more than a passing resemblance to the deserts of the Middle East.

It took mankind a couple of millennia to turn the fertile crescent into a wasteland, thanks to fossil fuels, we can lay waste

Africa has more than enough arable land and resources to feed itself solely with food produced from the continent. Their problems are political, and socioeconomic.

I don't have an answer to fix the problem, and I don't know enough about the situation and the history to give a very insightful explanation as to how it came about but it seems that the African people cannot govern themselves effectively. This goes back even to before Europeans arrived. They were subsistence farmers and hunter/gathers organized in tribal groups or regional empires that fought with their neighboring tribes when the Europeans came and that's mostly what they are still today. The only difference is that we provided them with terrible new weapons to kill each other much more effectively, and we established an amoral economic basis by which the most ruthless among them could gain much wealth and power by exploiting their kinsmen through cooperation with resource extracting imperialists.

I don't see a way out of this nightmare for them. Africa will remain mired in all of the worst aspects of humanity for the foreseeable future. Everything anyone does to try and help just addresses the symptoms, not the systemic problems which the West seems ill-equipped even to identify, much less remedy.

Underground reservoirs are not necessarily refilled by the next rain. Read up on such reservoirs found in North America. They were filled over many thousands of years and significantly drained by agriculture related drilling and pumping in decades. Every year agriculture has to drill deeper and deeper to find water.

It gets consumed, evaporates, and then it never rains again.

Of course it rains, the problem is that it does not necessarily rain where the water was harvested. Harvesting deep water reservoirs does not somehow change the fact that a region is a desert or arid region with little rainfall.

I don't care how much good that water might do today: I want to know how long it'll last if a billion people start sucking it up. Aquifers replenish, but only very slowly. Even the scientists behind the research are stressing that industrial-scale drilling will exaust the supply eventually.

Even the scientists behind the research are stressing that industrial-scale drilling will exaust the supply eventually.

Presumably it will last a long time, if they make sure to tightly regulate any tapping of industrial scale quantities,
ensure that the amount of water drawn out is less than the local replenishment rate, and
ensure that players are treated fairly, no one entity is allowed to hog the resource, and any entity that does
tap the resource pays a quantity-dependant price for doing so, to discourage waste.

There's no inherent reason that industrial-scale drilling has to be allowed to exhaust the supply

There's no inherent reason that industrial-scale drilling has to be allowed to exhaust the supply

Pffft. Silly rabbit. The inherent reason is humans. Someone with an interest in industrial scale wasting of water will pay the right people just enough to get them out of the way, and start depleting it as fast as they can, for as much or as little profit as they can make from it.

Presumably it will last a long time, if they make sure to tightly regulate any tapping of industrial scale quantities,
ensure that the amount of water drawn out is less than the local replenishment rate, and
ensure that players are treated fairly, no one entity is allowed to hog the resource, and any entity that does
tap the resource pays a quantity-dependant price for doing so, to discourage waste.

There's no inherent reason that industrial-scale drilling has to be allowed to exhaust the supply

Because this works so well for aquifers in modern, developed, industrial countries where the aquifer is fully within the borders of the only country using it? See e.g. the Ogallala Aquifer [wikipedia.org].

""Even in the lowest storage aquifers in semi arid areas with currently very little rainfall, ground water is indicated to have a residence time in the ground of 20 to 70 years." Dr Bonsor said."That was the only bit I saw that had any time period, and I'm not sure exactly would that means. The scientists are strongly suggesting smaller-scale bores, but we all know that none of the governments will listen. Even the US mid-west aquifier (sorry, forget its name) keeps dropping, and that area gets a ton more

I doubt if very many of the people suffering from continual Guinea worms they ingest from contaminated surface water would share your worry. They're too busy trying to yank two-foot-long spaghetti aliens out of their arms, legs, feet, and abdomens. Having a guaranteed uncontaminated water source from a gigantic aquifer would end their daily war against the alien invasion.

The point though is legitimate because the population has exploded with most people living not much different than they did a hundred years ago. Everyone shares this naive belief that all we need to do is feed the hungry people. Feeding them without education gives you two hungry people instead of one. Every documentary I've ever seen showing starving single mothers in Africa they ask how many kids they have and it turns out they are trying to raise 6 or 8 kids on $2 or less a day. It's impossible so most starve. The only sure cure for out of control fertility rates is education and improved lifestyles. Where are the lowest fertility rates in the world? Japan, the US and most of Europe where they have strong economies. The exception being religious groups that insist the members have as many kids as possible. Conditions weren't that different in this country a 100+ years ago except we had the resources to feed them. Send them drills and water pumps as well as condoms and tell the Pope to go fuck himself since they aren't willing to help feed the people his and the church's policies help create. If we've been exceeding the Earth's resources since the early 80s every one born since then will eventually have to find some place else to live. It's not opinion if the numbers are right it's a fact. The only real solution in the long run is that there are fewer people using the resources. If we don't fix the problem nature will do it herself. Fewer kids born or mass starvation, which is crueler?

Guinea worm is looking like it is on the verge of eradication thanks to a concentrated effort over the last 10 years, a 99% reduction over the last 25 years. This is through basic sanitation and proper treatment procedure with none of this no-holds-barred short term thinking you are proposing.

It just awaits the opening of certain war-torn areas to health workers, then it will be gone for good. Proposing to deplete a valuable resource in its name just makes you sound impetuous and stupid.

Unfortunately a good source of water would be just one more thing for the warlords to fight over. Check out what's going on in Sudan this week if you don't understand. The Darfur genocide wasn't a natural catastrophe.

We gave up on that game when we discovered that we didn't actually need lots of peasants. Now we just install corrupt governments and bribe them to let us take all of the natural resources. It's much cheaper and doesn't leave us with embarrassing colonies that we need to maintain.

Although I'm sure many will say this is inhumane, I suggest that this survey quietly disappear. Many of the United States' agricultural land is in danger of turning to dust due to several factors. Part of it is the poor use of land; Overuse of pesticides, chemical fertilizer, genetically engineered crops (the crops are not the problem, the business practices of companies like Monsanto are), and the loss of top soil due to erosion are just some of the problems. We have several states that are largely desert right now (the "dust bowl" was a ecological disaster caused by irresponsible farming practices). However, the other part of it is due to lack of access to fresh water. People are living in places that have tapped out their underwater reserves; Especially those in the southeastern United States. Several municipalities are embroiled in fierce legal battled over neighboring cities (and even states!) refusal to share their water. This is a situation that will only get worse over time; Already there is talk about southern states passing legislation or taking overt and aggressive action to divert water from the Great Lakes to areas of the south that soon will be uninhabitable without water relief -- others of course argue that the areas should never have been inhabited in the first place.

If the countries of Africa tap that resource, on one hand they will experience a sudden burst of economic activity and agricultural reform; and with it a corresponding explosion in population. However, there is already too much industrialization of the planet as it is, and with global warming going unaddressed due to a lack of cooperation by sovereign powers, an untempered entry into industry by so many new countries could cause a global ecological disaster that could leave most of the tropical regions of the planet devastated and unfarmable. If an industrialized country with access to state of the art technology, extensive scientific understanding, and sufficient natural resources, cannot solve these problems... I shudder to think what could happen if an entire continent did a history repeat.

The Great Lakes or a finite resource. The midwest is already draining them on it's own. I've seen photos of boats sitting on mud dozens of feet from water. I grew up in Michigan and I never heard of such a thing. Climate change has reduced the water flowing into the Great Lakes and irrigation is draining them. Build a giant irrigation pipe and you get the great mud lakes. Most of the food grown in this country relies on irrigation. When I was in Los Angeles we were all told to conserve water yet 90% went to

Many of the United States' agricultural land is in danger of turning to dust due to several factors. Part of it is the poor use of land; Overuse of pesticides, chemical fertilizer, genetically engineered crops (the crops are not the problem, the business practices of companies like Monsanto are), and the loss of top soil due to erosion are just some of the problems. We have several states that are largely desert right now (the "dust bowl" was a ecological disaster caused by irresponsible farming practices).

Citation needed. The dust bowl was a combination of factors, one of which was not realizing that the relatively cool/wet period at the end of the 19th century and early 20th when the land was brought under cultivation was unusual. But if you've ever been to the Midwest you would know that much of the soil there is loess [wikipedia.org], obviously the Dust Bowl had been repeated many times over millions of years.

...an aquifer was found in Africa it was drained dry due to wastage and abuse of resources. This isn't a miracle cure, guys. If used properly, it might reduce the stress on the land (so allowing it to recover, so increasing rainfall) but it is NOT a substitute for surface reservoirs, it is NOT a substitute for learning how to be efficient with resources, it is NOT infinite and it is NOT going to cure centuries (if not millenia) of neglect of Africa.

It's not new that there are huge groundwater resources in Africa. The only new thing in the article is that they mapped it in more detail then ever before. And these resources are also heavily utilized today. However, using groundwater for food production is not without great danger - the keyword here is salinification.

Congrats, you win the pertinent point award. I had to scroll down quite a ways to find your post, what, did all the Aussies go to bed already? They alluded to it in the article when the scientists said that this might not be the solution that they need for this problem.

See also the 1978 novel "Flyaway" and the results of surveys made in the years before that which meant the author could find this out by reading some information for tourists.What is new is the detailed map instead of finding it under just a few countries while looking for oil.

Gaddafi has built a pipe system to use the huge aquifer under Libya. My friend told me that this was the reason why NATO went to war in Libya but not in Syria. The latter had nothing to offer (a la oil etc.) but the former has a huge treasure, and you can't have someone who doesn't play ball with the rich guys in charge.

It's a bullshit explanation. NATO didn't go to war against Libya, the Libyan people went to war against Qaddafi, and NATO lent support. Also, precisely what does NATO have to gain by preventing the Libyans from having more water?

The largest underground network of pipes (2820 km) [2] and aqueducts in the world. It consists of more than 1,300 wells, most more than 500 m deep, and supplies 6,500,000 m3 of fresh water per day to the cities of Tripoli, Benghazi, Sirte and elsewhere.

All of this water is great! But with all of the corrupt governments throughout Africa who will ever get to benefit from it?

I've always felt that Africa is the richest continent. It's chock-full of minerals, oil, diamonds, arable land (some land better than other land but with the right techniques just about anything is possible)... The climate is warm to hot throughout much of the continent facilitating growing. Its people? If you go to the right places hard-working, skilled and eager to work. But its corruption is widespread. Without targeting that (much easier said than done) this water will either stay in the ground or will go to benefit some dictator or other "politician".

Having been to Africa, I can tell you that more freshwater wont solve the problem in the least. The water they get is not contaminated at the source. Much of it comes from wells, or Rivers and lakes. The rivers and lakes may have "Some" contamination... but that's not what the real problem is. The real problem is their horrible infrastructure. They lack even basic building inspection laws. Plumbing is done on-site, by whomever happens to be there. With no training in the field. The result is a haphazard public water supply infrastructure that is subject to contamination from the user.

A simple example is: Every bathtub that I saw in Africa did not have a shower. It had a sprayer that had a hose that led back to the side of the faucet. There was a hanger on the wall for... in every case that I saw the hanger had been long broken, and the sprayer lay in the bottom of the tub. If you fill the tub while leaving the sprayer laying in the water, you can get a siphon effect fairly easily. This draws dirty water from the tub back into the water supply. It's irrelevant where that water came from, it could have been triple distilled, it's now contaminated. This sort of setup is illegal in the united states for that very reason. There were thousands of other problems like this. Now imagine that your city had this sort of problem... ALL of the plumbing would have to be replaced... from the well to your faucet. The whole thing. How could you fix that? Now imagine it's an entire continent... and now you have a grasp of the size of the problem.

you can get a siphon effect fairly easily. This draws dirty water from the tub back into the water supply.

I am having a hard time understanding how this can happen. How can two feet of water pressure (depth of bathtub) cause siphoning of water from the tub into the high pressure water system. I don't think I could do this if I tried. If they have less than two feet of water pressure, then yes, they have infrastructure problems.

Perhaps you are talking about a venturi effect? If the sprayer comes off at an angle from the faucet/pipe used to fill the tub, you can possibly draw water backwards into the sprayer hose

you can get a siphon effect fairly easily. This draws dirty water from the tub back into the water supply.

I am having a hard time understanding how this can happen. How can two feet of water pressure (depth of bathtub) cause siphoning of water from the tub into the high pressure water system. I don't think I could do this if I tried. If they have less than two feet of water pressure, then yes, they have infrastructure problems.

Perhaps you are talking about a venturi effect? If the sprayer comes off at an angle from the faucet/pipe used to fill the tub, you can possibly draw water backwards into the sprayer hose but this is still downstream from the faucet and will not go back into the main water supply.

I've heard similar explanations for the separate hot and cold water taps in the UK. They say the hot water is not fit for drinking* and a mixer tap might cause a contamination of the cold, potable water supply. Similarly, this would require a serious problem in the infrastructure.

*(Microbiological issues. Here in Finland, we do advise against drinking hot water from the tap, because there is a marginal risk of heavy metal leaching from the plumbing, depending on the age/material of the series of tubes. O